This invention relates to gas tungsten arc welding (GTAW), and more particularly to a wire guide which extends through the tungsten electrode of gas tungsten arc welding apparatus.
Gas tungsten arc welding (GTAW) is a process wherein coalescence of metals is produced by heating them with an arc between an nonconsumable tungsten electrode and the work. A filler metal is utilized at least in those instances where the welding process is automatic or semi-automatic and where the base material to be welded is relatively thick, the filler material being a welding rod or wire which is conventionally fed through a conduit external of the gas nozzle which surrounds the tungsten electrode. Shielding of the electrode and the weld zone is obtained from an inert gas such as argon or helium which is fed through the nozzle so as to prevent oxidizing of the electrode, the filler wire and the weld material which would occur rapidly if exposed to air during welding. The GTAW process is especially useful for joining aluminum and magnesium which form refractory oxides, and also for the reactive metals such as titanium and zirconium. Because of the high quality weld provided for the above mentioned materials, the gas tungsten arc welding process is used extensively in the aircraft and aerospace industry.
One of the difficulties with the prior art GTAW apparatus is that the filler metal, which is in the form of a small diameter rod or wire, is fed through a guide which, as aforesaid, is external of the gas nozzle. Because of this outside clearance problems are encountered when welding confined portions of workpieces, and additionally in certain instances the wire may not be completely shielded by the shielding gas and becomes exposed to air so as to contaminate the weld metal thereby resulting in an improper weld.